Sir Alex Ferguson resolved to sell his captain Roy Keane, during a "venomous" exchange from which their relationship has never recovered, he reveals in his book My Autobiography

Ferguson for the first time gives his side of the incident during the 2005-06 season in which Keane slaughtered his team-mates on the club's television channel and was then sold to Celtic following a furious bust-up with the manager.

Ferguson risks reopening old wounds and passes judgment on Keane's management career by saying he lacks patience, that he "failed" at Sunderland and "came up short" at Ipswich Town, even with money to spend.

Labelling his one time talisman "a man of extremes", Ferguson traces their falling out to Keane's declining influence on the pitch and refusal to reshape his game to become a more deep-lying midfielder: "He thought he was Peter Pan. No one is."

He also accuses Keane, who will be a pundit on ITV's coverage of Arsenal v Borussia Dortmund on Tuesday night, of starting to think he was the manager. "The one thing I will not allow is a loss of control, because control was my only saviour," writes Ferguson.

Ferguson arrived at United's pre-season training camp in Portugal on the eve of the 2005-06 season to find Keane raging against the facilities and the house in which he had been put up.

After the infamous MUTV interview – in which he slated players including Kieran Richardson, Darren Fletcher, Alan Smith, Edwin van der Sar and Rio Ferdinand following a game against Middlesbrough – Keane suggested the whole squad gather to watch it together.

Ferguson had already told his captain the interview was a "disgrace" and a "joke". After they had watched the video, Van der Sar and Keane locked horns before the Irishman turned on his manager, accusing him of bringing his private life into the club with his dispute with the racehorse owner John Magnier over Rock of Gibraltar.

Roy Keane was a leader on the pitch but, according to Sir Alex Ferguson, became an unwelcome distraction as his career declined. Photograph: SHAUN, BOTTERILL/ALLSPORT

"The hardest part of Roy's body is his tongue," writes Ferguson. "What I noticed about him that day as I was arguing with him was that his eyes started to narrow, almost to wee black beads. It was frightening to watch. And I'm from Glasgow."

Carlos Queiroz, then assistant manager, told him it was "the worst imaginable spectacle" and in that moment Ferguson resolved that Keane, the rock on which United's success had been built and a hero to the fans, needed to be sold.

Asked at his press conference on Tuesday whether he expected Keane to respond, Ferguson said: "The nature of the man you can expect that, that is the personality he has. But the reason was I had to explain what happened. It happened so quickly. He criticised his team-mates. We could not release that video. It ended up with two young players being booed in Paris [against Lille] on the Wednesday.

"The meeting in the room was horrendous. I just could not lose my control in that situation. If I had let it pass I think the players would have viewed me differently.

"Throughout my career I have been strong enough to deal with issues like that. Roy absolutely overstepped the line. There was nothing else we could do."